RE: telnet vs ssh on Core equipment , looking for reasons why ?
From: Valdis.Kletnieks@vt.edu [mailto:Valdis.Kletnieks@vt.edu] Sent: Tuesday, July 31, 2001 3:10 PM
On Tue, 31 Jul 2001 14:59:25 PDT, Roeland Meyer said:
You are probably aware, but EFF published the DES crack. I understand that it is now an issue of cracking DES in less than 12 hours. 3DES is better but it only amounts to DES with a 128-bit key.
Actually, 3DES has a 112 bit effective key. However, although that's only double the key length, the *difficulty* is a bit more than twice as much. Assuming a brute-force of a 56-bit key in 12 hours, then a 112 bit key will take (given the same resources) 2**56 * 12 hours, which is about 864,691,128,455,135,232 hours which works out to 98,709,032,928,668 years, which is about 4,000 times the current estimated age of the universe.
This analysis of course assumes that the EFF crack is a brute-force, and not a result of differential cryptanalysis or exploitation of a flaw in the DES S-boxes or similar. Schneier's 'Applied Cryptography' lists an attack that's around 2**47 rather than 2**56, assuming you can get the victim to encrypt several gigabytes of text of your choosing with his key....
... and then they load it on www.distributed.net
On Tue, 31 Jul 2001 16:16:24 PDT, Roeland Meyer said:
... and then they load it on www.distributed.net
Assuming that *all 4 billion* possible IPv4 addresses download and run it, this cuts it *at most* down to 22,982 years. And that's assuming that the EFF attack is *ONE* host, and that *all 4 billion* have equivalent hardware. I don't see 4 billion copies of the EFF box on the net, do you? -- Valdis Kletnieks Operating Systems Analyst Virginia Tech
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